The requirement, in full
A recent passport-size picture, in jpg or jpeg, under 30 KB, and not an informal photo. FPSC states no pixel or centimetre dimensions.
That is taken from the Guidelines for Online Application Submission on the FPSC website, updated in September 2025, which this page links to. Because no dimensions are given, the tool crops to the standard 3.5 × 4.5 cm passport shape and writes that print size into the file. The 30 KB limit is the part that actually gets applications rejected, and it is the part this tool exists to settle.